One of the options in the configureCollectionAutoSplit commands is to set the per-collection chunk size. However, this value is not actually being used currently. We should start using this setting for the balancer and autosplitter.

On shards, we should read the value from the catalog cache. This will be up to date since configureCollectionAutoSplit triggers a refresh on all shards.

In the balancer, we should update the refresh function to use the catalog cache as well. It should refresh in the next balancer round and get the new settings.